Broadband microwave communications provide the opportunity for miniaturized systems generally unobtainable at lower frequencies. Components, including antennas, can make these systems very expensive, however.
Radio frequency communication with air and space platforms provides the opportunity to remotely track objects over large distances. Military operations especially have a need for tracking technology for air-to-ground Combat Identification (CID). This generally includes microwave communications.
As an example, a Digital Radio Frequency Tag (DRaFT) can provide flexible technology to allow radars such as Moving Target Indicator (MTI) and Synthetic Aperture Radar (SAR) to receive data from ground devices. At the frequencies used by these systems, small, lightweight and affordable RF Tags can provide for data extraction from unattended ground sensors and communication with vehicles and personnel throughout an area. This is particularly useful for the identification and location of combined units. Other advanced tag functions include additional communications capabilities for enhanced interoperability with identification and communications systems.
Ultra-wideband (UWB) systems provide the benefit of radio transmissions that use a very large bandwidth. This can convey more signal information including data or radar resolution. Although no set bandwidth defines a signal as UWB, systems using bandwidths greater than about ten percent are typically called UWB systems. A typical UWB system may use a bandwidth of one-third to one-half of the center frequency.
Broadband operation in the X, Ku, and K bands is desirable, but applicable biconical antennas are cost prohibitive and too large for applications. They can cost thousands of dollars and occupy a volume as large as a tennis ball. Currently, multiple antennas are required to cover this bandwidth, especially both above and below the horizontal plane.
FIG. 1 is a diagram of a prior-art microwave biconical antenna 100. It is costly and can be difficult to integrate into a microwave system.
FIG. 2 is a plot 200 of the FIG. 1 prior-art biconical antenna H-plane pattern. It has been normalized based on the average signal from −135 degrees to +135 degrees.
Current microwave broadband antennas are expensive, difficult to integrate into systems, and can have relatively narrow operating frequencies.